Omi-Ọṣun, literally meaning "Ọṣun's waters", is the northernmost source tributary of the Ọṣun River in southwestern Nigeria. The Omi-Ọṣun tributary rises from the eastern sector of the Yoruba hills and flows westwards into the Òyì River which subsequently flows southward along two deep gorges within the Oke-Ila quartzite ridges, (adjacent to  Oke-Ila Orangun), before its confluence with other rivers to form the main Osun.